[icalendar] Update to 6.1.2 (#13672)

Finish icalendar.prop annotations

stubs/icalendar/@tests/stubtest_allowlist.txt

@@ -12,3 +12,12 @@ icalendar.cal.Component.set_inline
 
 # Stubtest gets confused by multiple inheritance.
 icalendar.prop.vSkip.__new__
+
+# Stubtest incorrectly reports that stub argument "cls" should be
+# positional or keyword.
+icalendar.vBoolean.__new__
+icalendar.vFloat.__new__
+icalendar.vInt.__new__
+icalendar.prop.vBoolean.__new__
+icalendar.prop.vFloat.__new__
+icalendar.prop.vInt.__new__